Modern communications systems continue to place ever-increasing performance demands on communications devices. Handheld communications devices in particular are subject to increasingly rigorous demands of smaller size and increased efficiency. At the same time, consumers expect these devices to have a continuously growing set of features.
Consumers expect phones to be smaller, lighter, and to have longer talk times. Unfortunately, these desirable features often represent competing demands to be satisfied by the phone designer. For example, the simplest method of increasing talk time is to increase battery size, but this works against the goal of smaller size. One method of achieving increased talk time without increasing overall size is to make the device more efficient. This way, talk time as well as other desirable features can be enhanced without increasing the battery size.
Because the power amplifier is by far the largest consumer of power in handheld communications devices, increasing the efficiency of the power amplifier is very desirable. Increased power amplifier efficiency results in the ability to make smaller phones that have more features, including increased talk time. The demand for higher performance communications devices, and in particular, smaller phones with increased talk time, presents the phone designer with a difficult problem: how to design a power amplifier capable of operating efficiently over a wide dynamic range.
Accordingly, there is a significant need for an efficient power amplifier capable of maintaining high efficiency while operating linearly over a wid dynamic range.